My wife doesn't mind Opeth, although she prefers Mike's clean vocals.  She likes some metal (well, after 7 years of marriage, something's gonna give), though she prefers Japanese music.  Funny how she always gets the arse when I listen to Sigh, though... Still, she's more likely to listen to Zeppelin than Oasis or Blur these days.
<<<<<<But as you can see, my 2 year old daughter is much more clued up on things.  She was doing this while I was listening to Grand Magus.  If she ever sees a guy with long hair, she points the horns and shouts "METAL!" at him.  I taught her the latter part, but she worked out the long haired bit herself.  I have high hopes for her!